临江高岩面桥梁主墩基础的施工技术

随着社会发展,桥梁施工向更大规模、更大跨度发展,桥梁基础施工受地质条件和地理位置的影响越来越大。介绍了柳州市双拥大桥主墩基础为临江高岩层面的地理位置特点,采取了有效的施工方法 ,克服了地理位置给大桥基础施工带来的不利影响。

钢管格构立柱桩在盖挖法高岩面深基坑中的应用研究

针对如何解决高岩面深基坑传统格构立柱桩成孔工效低、垂直度控制低下,影响盖板及基坑支护结构的安全性问题,依据项目实际情况,通过钢管格构立柱桩在盖挖法高岩面深基坑中的应用研究,提出了“大桩变小桩、角钢改钢管”的钢管格构立柱桩替代方法,大大提高了成孔工效、保障格构立柱桩垂直度,提高盖板及基坑支护结构的安全性,有效地解决了传统格构柱在碰到硬度较高的片麻岩、花岗岩等岩层则难于成孔的施工难题。

Failure mechanism of bolting support and high-strength bolt-grouting technology for deep and soft surrounding rock with high stress

In deep underground mining, the surrounding rocks are very soft with high stress. Their deformation and destruction are serious, and frequent failures occur on the bolt support. The failure mechanism of bolt support is proposed to solve these problems. A calculation theory is established on the bond strength of the interface between the anchoring agent and surrounding rocks. An analysis is made on the influence law of different mechanical parameters of surrounding rocks on the interfacial bond strength. Based on the research, a new high-strength bolt-grouting technology is developed and applied on site. Besides, some helpful engineering suggestions and measures are proposed. The research shows that the serious deformation and failure, and the lower bond strength are the major factors causing frequent failures of bolt support. So, the bolt could not give full play to its supporting potential. It is also shown that as the integrity, strength, interface dilatancy and stress of surrounding rocks are improved, the bond strength will increase. So, the anchoring force on surrounding rocks can be effectively improved by employing an anchoring agent with high sand content, mechanical anchoring means, or grouting reinforcement. The new technology has advantages in a high strength, imposing pre-tightening force, and giving full play to the bolt supporting potential. Hence, it can improve the control effect on surrounding rocks. All these could be helpful references for the design of bolt support in deep underground mines.

Evaluation of Rock Fall Hazards Using Lidar Technology

Lidar （light detection and ranging） is a relatively new technology that is being used in many aspects of geology and engineering, including researching the potential for rock falls on highway rock cuts. At Missouri University of Science and Technology, we are developing methods for measuring joint orientations remotely and quantifying the raveling process. Measuring joint orientations remotely along highways is safer, more accurate and can result in larger and more accurate data sets, including measurements from otherwise inaccessible areas. Measuring the nature of rock raveling will provide the data needed to begin the process of modeling the rock raveling process. In both cases, terrestrial lidar scanning is used to generate large point clouds of coordinate triplets representing the surface of the rock cut. Automated algorithms have been developed to organize the lidar data, register successive images without survey control, and removal of vegetation and non-rock artifacts. In the first case, we look for planar elements, identify the plane and calculate the orientations. In the second case, we take a series of scans over time and use sophisticated change detection algorithms to calculate the numbers and volumes of rock that has fallen off the rock face.

复杂地质条件下紧邻地铁隧道基坑工程支护方案研究

为了解决高岩面地质条件下基坑支护方案的选型及邻近地铁隧道保护措施的问题,本文提出了基于地层稳定性分析结果的基坑支护方案选型方法。通过一实际工程,介绍了地层稳定性分析的具体应用过程,并结合三维有限元分析方法,研究了采用吊脚桩支护下的基坑工程开挖对周边地铁隧道的影响问题。最后利用基坑施工过程中的监测数据及邻近地铁隧道监测数据,验证了本文所提出的地层稳定分析方法的可行性和高岩面地质条件下吊脚桩基坑支护方案对邻近地铁隧道保护的有效性。